An enhanced vision system (EVS) for an aircraft is designed to enhance pilot situational awareness during the approach and landing phases of flight at night or during poor weather conditions by providing an infrared (IR) camera view of the outside environment. The imagery may be displayed conformally on a Head-up Guidance System of Head-Up Display, increasing both safety and operational capability of the aircraft.
Enhanced vision systems for aircraft utilize relatively high cost infrared sensors mounted to the external surfaces of the aircraft (fuselage, tail, etc.). The infrared sensors are thermal imagers configured to recognize sources of heat, such as incandescent light sources. Thermal imagers detect thermal radiation rather than photons and, as such, are not configured to differentiate colors associated with the source of the incandescent light. These colors may be critical to a correct interpretation of an aircraft scene (e.g. VASI or PAPI lighting, rabbit-lights, end lights, center lights, edge lights, taxiway lights). Further, thermal imagers are not configured to recognize “cold” sources of light, such as reduced energy consumption light emitting diode (LED) or fluorescent lights sources that are increasingly being used at many airfields.
The performance of infrared enhanced vision systems often lags in poor weather conditions. In particular, infrared sensor performance degrades during certain weather conditions such as high density fog and large rain drops. Performance degradation can be caused by increased infrared scattering, dominant absorption, weak propagation, etc.
Accordingly, there is a need for an improved system and method of providing an enhanced vision system in an aircraft. Further, there is a need for such a system configured to recognize “cold” sources of light. Yet further there is a need to such a system configured to be able to differentiate external light sources based on the color of the light source. Yet further, there is a need for such a system and method coupled to a head up guidance system to provide an enhanced conformal image. Yet further, there is a need for such a system and method configured to modify the conformal image based on a light intensity sensed by the enhanced vision system. Yet further, there is a need to provide useful imagery at a cost level below that of infrared technology.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.